My retirement visa expires in late November. I need to leave Thailand for an extended time around mid October. My question is can I renew my visa a month or so before? Then get a re-entry permit for my return. My return could be as long as a year from then or less. I know I can just re-apply for another retirement visa but, why have another hassle to take care of.

You can ask and show your tickets out. Sometimes they will do more than the normal 30 days early.

Most any office will do it 30 days early without question. In fact, its crazy to wait until the last minute. Reports are Jomtien/Pattaya will do two months early without question. I think with proven air tickets out, your chances of getting this service two months early are fairly good in most any office. But no guarantees. No problem in returning as long as your reentry permit is there and your permission to stay is still in effect.